The MR
findings in cerebral malaria show similar cerebrovascular lesions. Acute
hemorrhage and infarction have been shown 5 days after the onset of
neurological symptoms. In one patient, 1.5-T scans with T1- and T2-weighted
images showed increased signal intensity compatible with hemorrhage,
and hyperintense areas suggesting infarctions. Follow-up scans 24 days
later, after intravenous quinine, showed a decrease in the size of the
lesions and the patient's clinical condition had also improved. In another
patient, MR scans showed severe diffuse encephalopathy and a focal pontine
lesion, consistent with the neurological clinical signs. Cerebral scanning
can therefore provide information when patients with cerebral malaria
exhibit focal neurological signs. The cerebral edema may be sufficiently
severe in infants and young children to cause suture diastasis, which
can be recognized on skull radiographs. For the majority of patients
with cerebral malaria, imaging will not alter the immediate therapy:
CT or MR scans may be of more importance when neurological recovery
is incomplete. The imaging findings are nonspecific and noncontributory.
Unless a concomitant infarct or infection is suspected, there is usually
no reason to image the brain during cerebral malaria.

The kidneys
may become small and contracted in chronic malaria but the imaging findings
are nonspecific. In blackwater fever the kidneys enlarge and there is
renal failure.

The lungs
usually remain normal radiologically during acute malaria, although
clinical bronchitis occurs in children and responds to antimalarial
therapy. Pneumonia and bronchopneumonia may also occur, particularly
in the malnourished. As already noted, it has been suggested that children
in West Africa who have markedly high parasitemia may have abnormal
chest radiographs. The changes reported were a generalized increase
in interstitial markings (of unspecified origin). The interpretation
of interstitial markings on the chest radiographs of small children
can be very controversial and this report, based on one series, needs
confirmation. So many small children worldwide are affected by malaria
that it is surprising there are no similar reports. In some adults with
either falciparum or vivax malaria, the chest radiographs may show pleural
effusions, sometimes bilaterally. The lungs may show hazy areas of diffuse
interstitial and/or alveolar edema: these are nonsegmental, although
occasionally they may coalesce until there is lobar consolidation. The
most common interpretation is likely to be of viral or bacterial pneumonia,
but there is no clinical evidence to confirm this, and there is no response
to antibiotic therapy. However, the lungs do clear with treatment for
malaria; the radiographs should return to normal in 3 to 7 days, with
a minority taking a few days longer.

The severe
pulmonary edema, which is usually fatal, has no unusual radiological
characteristics (Fig.
46.2). There is no cardiac enlargement and no evidence of heart
failure: small pleural effusions have been reported. Pulmonary edema
can occur acutely and unexpectedly, even when the patient has been on
treatment for malaria for a few days. Early recognition offers the only
possibility of reversal. Unfortunately, even strenuous therapy may not
be successful.
Bowel involvement, even infarction, may lead to gastrointestinal symptoms;
gastroenteritis is a common complication of malaria but has no specific
radiological findings. It can be due to prophylactic drugs.

In summary,
the most important factor in diagnosing malaria is to be aware of that
possibility, and the most useful contribution to be made by a radiologist
is to remember that pulmonary changes and pleural effusions may be due
to malaria, particularly the severe pulmonary edema which has such a
poor prognosis.